Means for electrically transmitting imagery



July 1, 1930. F. M. ROBE I 1,768,634

MEANS'FOR ELECTRICALLY TRANSMITTING IMAGERY Filed March 11, 1927 gig" I 4 3 Patented July 1930 UNITED STATES PATENT OFFICE FRAN K MORSE ROBB, OF BELLETI'ILLE, ONTARIO, CANADA MEANS non ELECTRIGALLY TRANSMITTING IMAGERY Application filed March 11 1e27. Serial No. 174,527.,

without detection by the human ,eye-any dis- 1 tortion due to the rapid changes; to increase the efliciency'in the distribution of a pencil of light over surfaces concerned in the reproduction-of the pictureor image; to eliminate the use in this distribution ,of-the light, allclumsy and weighty machines, as may be seen in' the wheels or discs rotated at high speed by electric motors and carrying lenses or mirrors and such like, as employed in most previous television systems; and thereby be able to develop the speed far beyond the limits of such'machines;' to efiect the synchronization of the transmitting apparatus with the receiving apparatus, and to eliminate much complicated mechanism already in use for the purpose of synchronizing the operations at the receiving station with the operations performed at the sending station; to adopt in this inventionas far as possible standard parts in the apparatus, which are known as capable of carryingout. their own particular functions in other pursuits; to reduce the risks of failure by this adoption of tested devices and speed up the'reproduction; to obtain results in the operation of the 5 apparatus at the lowest cost consistent with efficiency and insure low maintenance charges; and generally ,to provide to the people at their homes or -at pub1icplaces 40 images from afar moving or otherwise that will be anexact showing of the image sent by the sending station, either in the form of a moving-picture or original'subject, and it consists essentially of the novel means em 4'5 ployed, whereby'the continuous and rapid distribution of a pencil of light at the sending and receiving stations is made a salient feature as set forth more fully in the description of the details and operation of the invention hereinafter and pointed out broadimage appears following the distribution of ly and specifically in the claims for novelty following. v

In the drawings, Figure l is a diagrammatic view showing the suggested relative positionsof'various members comprising the apparatus at the receiving and'sending stations.

Figure 2 shows a view screen on which the the pencil of. light thereover. Figure 3 shows a detail of the lens.

Figure 4 shows a detail of the photo-electric cell and amplifier.

'Like numerals of reference indicate corresponding parts in the various1figures. eferring to the drawings, one oscillograph of the sending set is indicated by the numeral 10, and is of electro-magnet type having an up "and down wire. 11, set between the poles of anelectro-magnet 12, a torsion screw '13 at the outer end, and the binding posts 14 and 15 at the inner end. The said binding posts of'the oscillograph are con nected to an electric circuit energized intermittently by an oscillating current and as the circuit includes the wire 11 the latter is energized in steady oscillations which are produced by any known means, such as oscillating radio vacuum tube or similar hook-up.

It is preferable, however, on account of the high frequency to be reached, to secure these oscillations through a radio vacuum tube and in this manner the invention will be described herein without limiting it to the use of an oscillating vacuum tube or any other .means of producing the oscillating current.

The oscillographlO vibrates the small mirror 16, which is of very light construction, so that the vibration may occur at the rate of one thousand to the second more or less, thereby providing the transverse movement of the pencil of light reflected from the mirror at the rate of one thousand to a second more or less.

The 'oscillograph 171carrying the mirror 18, which may be larger than the mirror 16 on account of the lesser number of vibrations, is set at right angles to the oscillograph 10, and vibrates at the rate of sixteen vibrations 1 to thesecond more or less, whichmoves the pencil of light in the other direction, that is to say, up and down at a much slower rate,

so as to produce through the compound motion thus produced, azig-z'ag movementof the light too fast to bevisible tothe eye.

The oscillograph is connected up the radio box 19 providing'the oscillating current at onethousand oscillations per secondmore or less as regulated by the dial 20, while the oscillograph 17 is connected up to the -radio box 21 providing the oscillating'cur rentat the. rate of sixteen oscillations'to' the second more or less, as regulated by the dial 22. 1 L 1 The object screen 23 belongsto the sending set and Carries the photograph tobe transmitted, or it may be a living person orjmoving picture as desired.

A strong pencil of light is directed upon the mirror 16 of the oscillograph 10, from which it is reflected to the mirror 18 of the oscillograph 17, and frornthence to the screen.

Some of the light reflected by the screen is pickedupby the lens 25 and concentrated on the photo-electric cell 26. The photo-electric cell is'connected to an-amplifying apparatus which greatly amplifies the electrical im-.

pulses from it. p

At the receiving end, the oscillograph 28 energized by the transmitting current vibrates the opaque disc 29 and the-movement of the said disc 29 controls the amount of light passing to, the oscillograph 30, which is electrically connected to one of the bindingl :posts of the oscillograph 10 and to the ra io box 19, thereby in operation synchr0- nizing with said oscillograph "10 and vibrating the mirror 31 at the rate of one thousand vibrations to the second more or less, as'rcgulated by the dial 20. The mirror 31 reflects the light passing the opaque disc 29 to the oscillograph 32 at right anglesto' the oscillograph 30 and particularly to the mirror 33 of the oscillograph 32L r The oscillograph 32 is connected toa binding postof the oscillograph 171mm to the radio'box 21 thereby synchronizing with the oscillograph 17 in its operation at the rate of sixteen vibrations to the second more or less, as regulated by the dial 22.

The light beam reflected to the. mirror 33.

In the operation of the invention, where a picture isto be transmitted, either aphotograph or a real object or living thing, such as the headand shoulders of a person,.the

beam light is turned'on the picture or object,

and the oscillators started :and tuned; up to their selected frequencies; i

For simplioitys sake, takefa jphoto pinned up on thetra'nsmitting screen, and it will be seen that the 5 0t of'light ismade to move over the face 0 a photo III a zig-zag at an'extremely high speed, thus exploring the whole surface from start to finish in the fractionof a second, and because the twovibra'ting-os'cillographs are operated atthe receiving'cnd in the same circuits and by the same oscillating hook-ups that operate these at the sending end they will always be in'perfect syn:-

chronizatio'n, therefore the spot of light on the viewingscreen will trace exactly the same path as the s 0t on the transmitting screen, both spots 0 light-will have precisely the same positions on the respective screens at any given instant. Y I

, As. the spot of light travels over the photo meteor less light will be reflected'fan'd picked to turn almost parallel with the beam of light from the lamp 35 used in the receiving set.

--In this way most of the light will-be let past'and will appear. on the viewingscreen at the proper place; but when the spot of lightv on the transmitting screen is travellingover' a dark area, such as a mans coat, very little light will be reflected to the photo-electric cell, because the most of it will beabsorbed by the black of the photograph, thus little or. no deviation will occur to the opaque disc and little or no'l'ight will get through to'the viewing screen, resulting in a dark area, appearingat the proper place on that screen.

It will thus be seen that all details ofthe photo, light and dark lines and area shadings and tones, will be faithfully transmitted and reproduced on the viewing-screen at the receiving end.

In place of a photograph-,9 real object may be placed in the position of the transmitting screen,'and the same action will tak'e'pla'ce and the object will be accurately and. faithfully reproduced on the receiving screen, but on account of the fact that the spot of light travels over the screen area from beginning to end at the rate of sixteen times per second more 1 or less, any motion'of the subject will 'be easily taken care of, such as the wave of a hand, any

change of expression-on the face, the turn of the head, and such like, in the same manner as in a motion picture, where so many pictures actual light and dark substance in them to reflector absorb more or less of the exploring spot of light, a modification of the invention is used, in which the beam lamp of the transmitter is eliminated and the lens and photoelectric cell put in its place. And the mirror 18' of the oscillograph 17 is slightly dlshed or concave with the focus point of the reflector fallin on the transmittin screen.

Wit 1 such a long focal ength as this mirror will have, the whole screen will be pretty well Within the limits of. the focus, that is, although theoretically there is only one position onthe screen where the focus will be exact, theinexactness of the focus at all other points will besosl-ight as to be negligible. V

Now in operation, this focus pointof the concave mirror replaces the exploring spot of light before used, and this focus point moves over the screen in the same way. Thus light is picked up point by point by this collector mirror 18 and conveyed to the photo-electric cell, ip other words, light from the light image on the screen is reflected to the ph0t0-elec trio cell from whatever point on the screen the focus point happens to be at in its zig-zag exploring. I

This device can be used to transmit living .scenesand real objects by projecting their images on to the screen in the same way as a camera projects an image on to a ground glass screen or onto a film. For great distances amplifyin apparatus can be used at thereceiving en to amplify all impulses;v further, the oscillograph 28 and its opaque disc may be eliminated and instead the impulses from the photo-electric cell used to vary the brightness of the filament of the electric light bulb or the are light or other synchronizing withan' oscillograph in a receiving setfand vibrating at fixed adjustable frequencies, mirrors carried by said oscillographs and vibrating coincidently therewith, an oscillograph in a transmitting set synchronizing with an oscillograph in a receiving set and vibrating at fixed adjustable lower frequencies than the aforesaid oscillographs, vmirrors carried by the lower frequenc oscillographs in angular relatlon to the a oresaid m1rrors, said mirrors having a concaved member, a screen having the light directed thereon by the transmitting mirrors, a photo-electric cell, a lens introduced be tween the screen and the photo-electric cell,

means for amplifying the electrical impulses from said photo-electric cell, an oscillograph energized by the'transmitting current and a mask vibrated thereby and timing the passage to the receiving high frequency mirror, a receiving screen, and lights affording the beams required for the transmission of the icture.

FRANK MORSE ROBB.

electric light used in the beam lamp of the receiver.

In practice it may be possible to eliminate three of the line wires by connecting them all to the ground and completing their cir cuits that way, but this will be carried out in the various installations according to the conditions of use.

The use of the device is not restricted to transmitting pictures over wires, but may be done by the use of. diflerent radio wavelengths, all transmitted simultaneously and received and sorted out. coincidently so-thatthe transmission may be accurately done by radio.

What I claim is i In means for electrically transmitting imagery, an oscillograph in a transmitting set Signed at Toronto this 15 day of Fe ruary, 

